Slight gas odor from Lennox furnace

Discussion in 'HVAC Heating & Cooling' started by vtxdude, Dec 13, 2009.

  1. vtxdude

    vtxdude New Member

    Messages:
    127
    Location:
    NH
    Model # is C26-21-1

    I had the cover off of the furnace today and thought I caught a whiff of natural gas...not overpowering and only detectable if I stuck my face right up at a certain place in the furnace..it is not spread to the cellar and doesnt seem to be growing

    Take a look at this pic

    [​IMG]


    The smell is coming from the upper right hand corner of the silver box the best I can tell...right to that the right of that top bolt on right...at the very corner(s) of each side of the box next to top bolts there is a small opening into the box...they look like they were built that way

    You know maybe it has always been like this and I am just noticing because I have been super wary of smells lately......

    Is this something I should be worried about?
  2. vtxdude

    vtxdude New Member

    Messages:
    127
    Location:
    NH
    I just had National Grid (gas Company) and he used some sort of meter on it...it stayed zero for almost the whole time he checked with it going to 0.05 briefly. He said that there may be something wrong with the gas valve but since he was not a plumber or HVAC guy he could not be sure.

    In any event he said that everything checked out fine even with that minuscule reading...he used that meter on every connection he saw in the furnace and in the cellar and it all checked out at either 0 or 0.05

    He said if he thought there was any danger he would have shut everything down and red flagged the place

    If it is the gas valve is that a difficult and costly repair?


    The smell seems to be coming from this opening but this opening has always been here..it looks like it is supposed to be there

    [​IMG]




    Could it be the gas valve is allowing gas to get into burn chamber when it is not supposed to be?

    Like I said the gas company guy said the meter is very powerful and if there was a danger it would have picked it up


    Thoughts on next step...if I walk by the furnace you don't smell it..if you stick your face inside you get that faint whiff
  3. vtxdude

    vtxdude New Member

    Messages:
    127
    Location:
    NH
    Does anyone have any ideas?
  4. Ian Gills

    Ian Gills Senior Robin Hood Guy

    Messages:
    2,777
    Location:
    USA
    It might just be a loose connection somewhere on the gas lines or even on the pilot tube (if you have one). The smell of gas often drifts from where it originates.

    You did the right thing and called him out and he would have shut the gas off if there had been any danger. Their equipment is extremely sensitive.

    Yes it is difficult and yes it is costly. They rarely fail, especially with the symptoms you are experiencing. I had one fail and I'll tell you about that if you like. I do not think it is that.

    This is a tricky one. You could try and call a pro, and have him tighten the connections up. Or just leave it. The risk is that the pro comes out, tinkers and you can still smell the gas.

    Have him tighten the connections on the water heater too. Remember what I said about the smell of gas drifting.

    Actually, I remember you said you just had a WH installed and had other odor issues with that. Is that correct? If so, I bet it is the connection to that.
    Last edited: Dec 14, 2009
  5. vtxdude

    vtxdude New Member

    Messages:
    127
    Location:
    NH
    The gas company guy said that a hvac guy should have a meter he can attach right to the gas valve and from that he would be able to tell me the pressure and if gas is leaking into the combustion chamber...in other words be able to tell if valve has issues?
  6. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    It's called a manometer and the HVAC guy should have one. They're crucial when adjusting the input to an appliance.
  7. Ian Gills

    Ian Gills Senior Robin Hood Guy

    Messages:
    2,777
    Location:
    USA
    I've got one.

    But gas valves rarely fail like that.
  8. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I would contact the furnace manufacturer about those pinholes.
  9. vtxdude

    vtxdude New Member

    Messages:
    127
    Location:
    NH
    What is weird is those holes have always been there..if you look it looks like they are there by design??
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